1. Fit a thicker spacer between the carb and the head, minimum 1/4" thick, fit longer carb mounting studs if needed. This reduces the heat getting to the carb.
2. Fit a choke, oddly my B44 starts well when hot with the fitted choke turned on, it has to be turned off immediately as it 8 strokes as soon as it catches. Believe this helps the carb as on singles, the pull on the fuel is low and the hot fuel loses its volatile parts so less likely to ignite so a temporary increase in fuel helps.
3. Fit an extended throttle screw, easy to adjust with a gloved hand so with a hot start you can turn it in 1/4 turn as this can also help.
4. Before I fitted the choke I found opening the valve lifter and kicking the engine over until a loud bang came out the exhaust and then closing the valve lifter before kicking for starting worked. Maybe it cleared out some fuel that had lost its volatile part from being hot.